/*
 * Copyright 2014 mango.jfaster.org
 *
 * The Mango Project licenses this file to you under the Apache License,
 * version 2.0 (the "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at:
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations
 * under the License.
 */

package org.jfaster.mango.util.logging;


import org.slf4j.LoggerFactory;
import org.slf4j.helpers.NOPLoggerFactory;

import java.io.OutputStream;
import java.io.PrintStream;
import java.io.UnsupportedEncodingException;

/**
 * Logger factory which creates a <a href="http://www.slf4j.org/">SLF4J</a>
 * logger.
 */
public class Slf4JLoggerFactory extends InternalLoggerFactory {

  public Slf4JLoggerFactory() {
  }

  Slf4JLoggerFactory(boolean failIfNOP) {
    assert failIfNOP; // Should be always called with true.

    // SFL4J writes it error messages to System.err. Capture them so that the user does not see such a message on
    // the console during automatic detection.
    final StringBuffer buf = new StringBuffer();
    final PrintStream err = System.err;
    try {
      System.setErr(new PrintStream(new OutputStream() {
        @Override
        public void write(int b) {
          buf.append((char) b);
        }
      }, true, "US-ASCII"));
    } catch (UnsupportedEncodingException e) {
      throw new Error(e);
    }

    try {
      if (LoggerFactory.getILoggerFactory() instanceof NOPLoggerFactory) {
        throw new NoClassDefFoundError(buf.toString());
      } else {
        err.print(buf.toString());
        err.flush();
      }
    } finally {
      System.setErr(err);
    }
  }

  @Override
  public InternalLogger newInstance(String name) {
    return new Slf4JLogger(LoggerFactory.getLogger(name));
  }
}
